Question

Rank the following compounds in order of decreasing vapor pressure.
Rank from highest to lowest vapor pressure

Answer 1

\[CH _{4}\] \[CH _{3}CH_{2}CH_{2}CH_{2}OH\] \[CH_{3}CH_{2}CH_{2}CH_{3}CH_{3}\] \[CH_{3}CH CH_{2}CH_{3}\] (coming off the CH on the fourth species is a \[CH_{3}\] joined by single bond

Answer 2

Look for the order of intermolecular forces. The weaker the forces, the higher the vapor pressure. The only important forces here are some weak dipole forces in the alcohol, and the London forces for the rest. Hopefully you know how London forces scale with the size and shape of the molecule.